Method of and apparatus for manufacturing workpieces having polygonyl inner and outer contours

Abstract

Methodwise this disclosure relates to the manufacture of workpieces having polygonal inner or outer contours based upon radii of predetermined inner and outer circles with n being the number of angles of the desired polygon, the method including the steps of rotating a workpiece about its axis, moving the tool along an ellipsoidal path while in contact with the rotating workpiece with tool travel along the ellipsoidal path having velocity varying generally sinusoidally as a function of tool location, said ellipsoidal paht is radially offset from the workpiece axis of rotation and its width generally corresponds to the difference between said inner and outer radii, and rotating the workpiece about its axis for a duration of time longer than the duration of movement of the tool along the ellipsoidal path by said factor n.

I claim: 
     
       1. A method of moving a tool to form a polygonal outline having inner or outer polygonal contours based upon radii of predetermined inner and outer circles with n being the number of angles of the desired polygonal outline comprising the steps of rotating a workpiece to be outlined about a fixed axis, moving a tool along an ellipsoidal path in a plane perpendicular to the workpiece axis while in contact with the rotating workpiece with tool travel along the ellipsoidal path having a velocity varying generally sinusoidally as a function of tool location, said ellipsoidal path is radially offset from the workpiece axis of rotation, and synchronizing the relative rotation of the tool and the workpiece about its axis for a duration of movement of the tool along the ellipsoidal path by said factor n. 
     
     
       2. The method as defined in claim 1 wherein the width of the ellipsoidal path travelled by said tool corresponds generally to the difference between the radii of the inner and outer circles of the desired polygonal outline. 
     
     
       3. The method as defined in claim 1 wherein the length of the ellipsoidal path travelled by the tool is approximatley twice its width. 
     
     
       4. The method as defined in claim 1 wherein the width of the ellipsoidal path travelled by the tool is less than half its length thereby generating a polygonal outline having outwardly curved sides. 
     
     
       5. The method as defined in claim 1 wherein the width of the ellipsoidal path travelled by the tool is larger than half its length thereby generating a polygonal outline having inwardly curved sides. 
     
     
       6. The method as defined in claim 1 wherein the ellipsoidal path is located relative to the workpiece such that its longer sides are tangent to the inner and outer circles of the desired polygonal outline. 
     
     
       7. The method as defined in claim 1 including the additional step of subsequently displacing the ellipsoidal path travelled by the tool further outwardly away from the axis of the workpiece thereby generating a polygonal outline having rounded corners. 
     
     
       8. The method as defined in claim 1 wherein the workpiece is metal and the polygonal outline is a hole cut by the cutting tool upon relative movement of the tool and workpiece progressively toward each other. 
     
     
       9. Apparatus for moving a tool to form a polygonal outline having inner or outer polygonal contours based upon radii of predetermined inner and outer circles with n being the number of angles of the desired polygonal outline comprising means for rotating a workpiece to be outlined about a fixed axis, means for moving a tool along an ellipsoidal path in a plane perpendicular to the workpiece axis while in contact with the rotating workpiece with tool travel along the ellipsoidal path in a plane perpendicular to the workpiece axis while in contact with the rotating workpiece with tool travel along the ellipsoidal path having a velocity varying generally sinusoidally as a function of tool location, said ellipsoidal path being radially offset from the workpiece axis of rotation, and means for synchronizing the relative rotation of the tool and the workpiece about its axis for a duration of time longer than the duration of movement of the tool along said ellipsoidal by the factor n. 
     
     
       10. The appratus as defined in claim 9 wherein said rotating means is a chuck gripping said workpiece with the face of the latter to be machined lying in the path of said ellipsoidal oath. 
     
     
       11. The appratus as defined in claim 9 wherein said control means includes a planet gear meshed with an internally toothed stationary ring gear, said planet gear carries an eccentrically mounted crankpin, and means coupling said tool to said crankpin. 
     
     
       12. The appratus as defined in claim 11 including a universal joint in part defining said coupling means. 
     
     
       13. The apparatus as defined in claim 12 wherein said universal joint is located on an extension of the axis of the chuck and workpiece. 
     
     
       14. The apparatus as defined in claim 12 wherein the universal joint is adjustable along an extension of the pivot axis of the chuck and workpiece for movement toward or away therefrom. 
     
     
       15. The apparatus as defined in claim 12 wherein the tool is a cutting tool.